The lower frequency of a bass guitar makes the cone move further back and fourth, this can damage (DESTROY) the voice-coil if it goes over its limit. Bass speaker drivers have more travel then the guitar drivers.
Some people use guitar cabs for bass, but have they replaced the drivers with special bass drivers ?
I would not use even a 1/4 of the power that the cab is rated for if using a bass guitar.
Even specially made Bass speaker drivers can be down-rated by 75% depending on the cab they are in, even when the cab is made for that speaker.
Bass cabs also reduce the usable power rating if you do not use a High Pass Filter, Ie- 400w above 80Hz but only 250w above 40Hz, that's why some Bass players have high pass filter stomp boxes they can use.
A 4 string Bass can go down to 40Hz, but hardly any cabs can go that low, what you hear is the harmonics at 80Hz+ from the 40Hz string. (Your brain tells you it belongs to the 40Hz)
I know that and I am not a bass player (Yet).
Be very very careful, a new guitar speaker driver costs nearly as much to replace as a small cheap Bass Cab. ( or you can go ahead and learn the hard way like many people before you have)